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(11) | EP 1 691 483 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Interface circuit, power conversion device, and vehicle-mounted electric machinery system |
(57) The invention relates to an interface circuit (4) capable of reliably transmitting
signal even when there is fluctuation in the potential difference in reference potentials
between circuits between which signal transmission is carried out. An interface circuit
(4) is comprised of a level shift circuit (20) and a potential selection circuit (10)
for selecting the potential of a power supply voltage for operating the level shift
circuit (20). The potential selection circuit (10) selects one of a plurality of input
potentials. The level shift circuit (20) receives a voltage pulse having a first potential
as reference potential and outputs a voltage pulse having a second potential as reference
potential. The level shift circuit (20) is operated on the basis of both a potential
difference between the output potential from the potential selection circuit and the
first potential and a potential difference between the selected potential and the
second potential.
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